GSM/GPRS Module Series
M66 Hardware Design
M66_Hardware_Design Confidential / Released 19 / 80
TXD
17
DO
Transmit data
V
IL
min=0V
V
IL
max=
0.25×VDD_EXT
V
IH
min=
0.75×VDD_EXT
V
IH
max=
0.2
V
OH
min=
0.85×VDD_EXT
V
OL
max=
0.15×VDD_EXT
If only use
TXD, RXD and
GND to
communicate,
recommended
to keep other
pins open.
RXD
18
DI
Receive data
DTR
19
DI
Data terminal ready
RI
20
DO
Ring indication
DCD
21
DO
Data carrier detection
CTS
22
DO
Clear to send
RTS
23
DI
Request to send
Debug Port
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
DBG_
TXD
39
DO
Transmit data
Same as above
If unused,
keep these
pins open.
DBG_
RXD
38
DI
Receive data
Auxiliary Port
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
TXD_
AUX
29
DO
Transmit data
Same as above
If unused,
keep these
pins open.
RXD_
AUX
28
DI
Receive data
SIM Interface
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
SIM_ VDD
14
PO
Power supply for SIM card
The voltage can be
selected by software
automatically. Either
1.8V or 3.0V.
All signals of
SIM interface
should be
protected
against ESD
with a TVS
diode array.
Maximum
trace length is
200mm from
the module
pad to SIM
card holder.
SIM_ CLK
13
DO
SIM clock
V
OL
max=
0.15×SIM_VDD
V
OH
min=
0.85×SIM_VDD
SIM_ DATA 11
IO
SIM data
V
IL
max=
0.25×SIM_VDD
V
IH
min=
0.75×SIM_VDD
V
OL
max=
0.15×SIM_VDD
V
OH
min=
0.85×SIM_VDD
Quectel
Confidential